aahh ghost whisperer , i like this series .. this is just a "Serial Fiction" , after death our soul are going back to our lord , as in the holly quran ..."Every soul shall have a taste of death: and We test you by evil and by good, by way of trial. To Us must you return." (21:35)

ghost is a bad energy,it has no face actually,but our imagination gives this a face, and some time when soul has the gap between taking birth again then they travels in the another plane "sphere, and some times they gets seen by people in some situations, but its also true that once you are full of positive energy and pure then ghost can never stays at these kind of people and places,and no ghost can be forever, bcz every soul takes birth again and again until it wont reach to the stage where it will finally merge in universal energy

Of course not, they are just fantasy. Like unicorns or trolls.